Method for manufacturing semiconductor device

ABSTRACT

An object is to suppress discharge due to static electricity generated by peeling, when an element formation layer including a semiconductor element is peeled from a substrate. Over the substrate, the release layer and the element formation layer are formed. The support base material which can be peeled later is fixed to the upper surface of the element formation layer. The element formation layer is transformed through the support base material, and peeling is generated at an interface between the element formation layer and the release layer. Peeling is performed while the liquid is being supplied so that the element formation layer and the release layer which appear sequentially by peeling are wetted with the liquid such as pure water. Electric charge generated on the surfaces of the element formation layer and the release layer can be diffused by the liquid, and discharge by peeling electrification can be eliminated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing asemiconductor device, and relates to a technique for separating anelement formation layer including a semiconductor element from asubstrate which is used at the time of manufacture.

In the present invention, a semiconductor device to be an object ofmanufacture includes a semiconductor element which can function by usingsemiconductor characteristics and general devices which function byusing a plurality of semiconductor elements.

As the semiconductor element, a MOS transistor, a transistor such as athin film transistor, a diode, a MOS capacitor, and the like are givenas examples. In addition, the semiconductor device includes anintegrated circuit having a plurality of semiconductor elements, adevice having a plurality of integrated circuits, or a device having anintegrated circuit and another element. The integrated circuit includesa memory circuit such as a CPU, a ROM, or a RAM, for example.

The device having a plurality of integrated circuits and the devicehaving an integrated circuit and another element include, for example, aliquid crystal module substrate, a liquid crystal module using thismodule substrate, a liquid crystal display device using this modulesubstrate, an EL (electroluminescence) module substrate, an EL moduleusing this module substrate, an EL display device using this modulesubstrate, an electronic device in which the liquid crystal module orthe EL module is used as display means, an IC chip which is providedwith an antenna and capable of wireless communication, an electronic tagprovided with such an IC chip, an IC card, and the like.

2. Description of the Related Art

A technique has been developed, in which after an integrated circuit isformed of a semiconductor element such as a thin film transistor (TFT)over a base material such as a glass substrate or a quartz substrate,the base material used in manufacturing the integrated circuit istransferred to a plastic film base material. A step of separating theintegrated circuit from a substrate used in manufacture is necessary totransfer the integrated circuit to another base material. Therefore, atechnique has been developed, in which the integrated circuit is peeledfrom the substrate.

For example, the following peeling technique using laser ablation isdescribed in Reference 1 (Japanese Published Patent Application No.H10-125931). A separation layer formed of amorphous silicon or the likeis provided over a substrate, a layer to be peeled which is formed of athin film element is provided over the separation layer, and the layerto be peeled is attached to a transfer body with an adhesive layer. Theseparation layer is ablated by laser beam irradiation, so that peelingis generated in the separation layer.

In addition, a technique in which peeling is performed with physicalforce such as human hands is described in Reference 2 (JapanesePublished Patent Application No. 2003-174153). In Reference 2, a metallayer is formed between a substrate and an oxide layer, and a layer tobe peeled and the substrate are separated from each other by using weakbonding at an interface between the oxide layer and the metal layer andgenerating peeling at the interface between the oxide layer and themetal layer.

It is known that, when peeling is generated, electric charge isgenerated on surfaces of two separated layers to be easily charged. Thisphenomenon is called peeling electrification. Since surfaces of twolayers are close to each other at the moment when peeling is generated,capacitance is generated between these surfaces. When peeling proceeds,the capacitance is reduced with increase in a distance between twolayers. However, the amount of electric charge generated by peelingelectrification is not changed; therefore, a potential of the surface ofthe layer increases in inverse proportion to the capacitance. When thepotential of the surface of the peeled layer increases, electric chargewhich is charged on the surface of the layer discharges toward inside ofthe layer in some cases.

Accordingly, when an object to be peeled is an integrated circuit, asemiconductor film, an insulating film, a conductive film, or the likeis destroyed by being melted due to heat generated by discharge. As aresult of this, a semiconductor element does not function in some cases.Even when the semiconductor element can operate without receiving damagewhich can be seen by appearance, a semiconductor or an insulatordeteriorates due to high potential application and the semiconductorelement does not show expected characteristics in some cases. Therefore,when discharge due to static electricity is generated, there is apossibility that the semiconductor element can be destroyed, or theintegrated circuit itself using the semiconductor element cannot beoperated normally due to characteristic deterioration.

Destruction of a semiconductor element or the like due to electrostaticdischarge (hereinafter referred to as “ESD”) is called an electrostaticbreakdown. The electrostatic breakdown is one of causes which greatlyreduce yield. As a conventional method for avoiding the electrostaticbreakdown, there are a method in which discharge due to staticelectricity is not generated and a method in which damage caused bydischarge to the semiconductor element is suppressed even when dischargeis generated due to static electricity. As the former method, a methodfor eliminating generated static electricity by providing an ionizer insemiconductor manufacturing equipment is known. A typical example of thelatter method is a method for manufacturing a protection circuit with asemiconductor element, and a high potential generated by discharge canbe prevented from being applied to the semiconductor element because ofthe protection circuit.

Even when static electricity is generated, the electrostatic breakdownis not generated as long as discharge does not occur. Discharge is easyto be generated when a potential difference between two objects islarge. Accordingly, the ionizer is a device for supplying a positive ionand a negative ion to the air which serves as a path of discharge andfor not generating a large potential difference which brings dischargebetween the objects. However, since discharge due to peelingelectrification is an instantaneous event in which two layers areseparated, elimination of electric charge by the ionizer is not in timein some cases.

In addition, in the case of providing a protection circuit, whenelectric charge of discharge passes through the protection circuit, theprotection circuit functions; therefore, destruction of a semiconductorelement can be avoided. However, in peeling electrification, since thesurfaces of two layers to be separated are charged, the pass ofdischarge does not always pass through the protection circuit.Accordingly, in peeling electrification, the electrostatic breakdown isnot sufficiently prevented by the protection circuit.

For example, a method for preventing discharge due to peelingelectrification is described in Reference 3 (Japanese Published PatentApplication No. 2005-79395, referred to Scope of Claims, Lines 42 to 48in Page 9). A conductive film is formed over a substrate, and a stackincluding a semiconductor element or the like is formed thereover. Bygenerating peeling at an interface between the substrate and theconductive film and diffusing electric charge generated in peeling inthe conductive film, destruction and characteristic deterioration of thesemiconductor element due to electric charge is avoided.

However, by a peeling method of Reference 3, the conductive film remainsin a lower portion of the stack. Depending on an intended purpose of thestack, the conductive film becomes an obstacle and an expected intendedpurpose cannot be carried out because of the conductive film in somecases. In such a case, it is necessary to remove the conductive film inthe peeling method described in Reference 3.

SUMMARY OF THE INVENTION

One object of the present invention is to avoid destruction andcharacteristic deterioration of a semiconductor element due to electriccharge generated by peeling. In addition, in Reference 3, although alower surface of a semiconductor element after peeling is limited to aconductive film, another object of the present invention is to permit usto select a high-resistant insulating material for a surface of thesemiconductor element side after peeling.

In order to solve the foregoing problems, the present invention includesmeans for not permitting to discharge electric charge charged by peelingeither inside of two separated layers. More specifically, one feature ofa method for manufacturing a semiconductor device of the presentinvention is that a surface which appears by separating an elementformation layer including a semiconductor element is wetted with liquidwhen the element formation layer is separated from a substrate.

In addition, in the present invention, a release layer is preferablyprovided so as to perform peeling easily by applying force in order thatthe element formation layer is separated from the substrate by applyingforce to the element formation layer or the like. One feature of anothermethod for manufacturing a semiconductor device of the present inventionis that the release layer is formed over the substrate, the elementformation layer including the semiconductor element is formed over therelease layer, and force is applied, so that peeling is generated at aninterface between the release layer and the element formation layer, andthe element formation layer is separated from the substrate while asurface which appears by peeling is being wetted with liquid ormoistened.

A portion where peeling is generated may be not only at the interfacebetween the release layer and the element formation layer but also at aninterface between the release layer and the substrate, or the inside ofthe release layer.

In order to wet (including to moisten) the surface which appears bypeeling with liquid, liquid may be supplied to a surface whichsequentially appears by peeling. One method for supplying liquid is amethod for dropping or pouring liquid. Another method is a method forspraying liquid in an atomized form or in a vaporized form. Anothermethod is a method for separating the element formation layer from thesubstrate while the substrate is being immersed in liquid. Anothermethod is a method for releasing liquid from liquid holding means whilethe element formation layer is being separated when the liquid holdingmeans such as sponge or cloth containing liquid is put in a gapgenerated by peeling.

As liquid for wetting the element formation layer or the like, liquidwhich does not deteriorate a material that forms the element formationlayer, the release layer, and the substrate; or liquid which does notproduce a product by reacting with these materials is preferably used.This is because a reaction product might contaminate the semiconductordevice and a step of washing the reaction product is needed. As liquid,liquid which does not function as an etchant with respect to the elementformation layer, the release layer, and the substrate is preferablyselected.

As liquid which is used for a method for manufacturing a semiconductordevice of the present invention, pure water can be used. In addition, asliquid, an aqueous solution which has lower resistivity than pure watercan be used. That is, an aqueous solution in which a substance isdissolved in water as a medium can be used. The property of an aqueoussolution may be any of acid, alkaline, or neutral. For example, anaqueous solution in which acid or a base is dissolved, an aqueoussolution in which salt (salt may be any of acid salt, alkaline salt, andnormal salt) is dissolved, or the like can be used.

As a substance which is dissolved in water, molecules which become gasat normal temperature (25° C.) under atmospheric pressure are preferablyused. As such a substance, there are carbon dioxide and hydrogenchloride, for example. In the case where a substance is salt, it ispreferable to use salt which functions as a surfactant, because asurface can be easily wetted when the surfactant is dissolved in water.

In addition, liquid used for a method for manufacturing a semiconductordevice of the present invention is a mixed solution of water andvolatile liquid, and desirably contains at least 0.1% water. An organicsolvent such as ethanol or acetone can be used for volatile liquid.

In addition, a technique of the present invention is not limited to amethod for manufacturing a semiconductor device and can be used for amethod for manufacturing a structural object including a step ofseparating a structure in which one layer or a plurality of layers arestacked from a substrate. That is, the present invention relates to amethod for manufacturing a structural object in which a structural layerincluding one layer or a plurality of layers is separated from thesubstrate, and has a feature in which a surface that appears byseparating the structural layer from the substrate is wetted withliquid. When the structural object is manufactured, similarly to thesemiconductor device of the present invention, the release layer ispreferably provided between the substrate and the structural layer.

Discharge is a phenomenon in which a current instantaneously flows to aportion where a current does not flow normally, such as an insulator ora semiconductor, due to a high potential difference. By wetting ormoistening a surface which appears by peeling, electrical resistance ofthe surface can be reduced. As a result of decreasing electricalresistance, electric charge which is generated by peelingelectrification diffuses on the wetted surface; therefore, a potentialcan be prevented from being increased as a potential of the surfacewhich appears by peeling generates discharge. That is, according to thepresent invention, discharge due to peeling electrification can beprevented.

According to the present invention, since discharge due to peelingelectrification is not generated, yield can be improved in a method formanufacturing the semiconductor device including a step of separatingthe substrate and the element formation layer. In addition, sincecharacteristic deterioration of the semiconductor element due to theelectrostatic breakdown can be eliminated, reliability of thesemiconductor device can be improved according to the present invention.

In addition, electric charge generated by peeling cannot be dischargedeither inside of two separated layers by the method of the presentinvention. Therefore, even when a lower surface of the element formationlayer is formed of an insulating material, the semiconductor elementincluded in the element formation layer can be prevented from beingdestroyed by static electricity generated due to peeling electrificationand characteristics of the semiconductor element can be prevented frombeing deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram to illustrate thatan element formation layer 11 is formed over a substrate 10.

FIG. 2 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram to illustrate thata support base material 13 is fixed to the upper surface of the elementformation layer 11.

FIG. 3 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a cross-sectional view toillustrate that peeling is generated at an interface between the elementformation layer 11 and a release layer 12.

FIG. 4 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram showing thatpeeling proceeds more than FIG. 3 at an interface between the elementformation layer 11 and the release layer 12.

FIG. 5 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram showing that theelement formation layer 11 is separated from the substrate 10.

FIG. 6 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram to illustrate thata first flexible substrate 18 is fixed to a lower surface of the elementformation layer 11 and the support base material 13 is removed.

FIG. 7 is a cross-sectional view of a semiconductor device manufacturedby a manufacturing method of the present invention.

FIG. 8 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram to illustrate thatliquid is supplied by using liquid holding means.

FIG. 9 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device and is a diagram to illustrate thatliquid is supplied by using liquid holding means.

FIG. 10 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is across-sectional view of a stack formed of a release layer 101 and anelement formation layer 102 over a substrate 100.

FIG. 11 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram toillustrate that a groove 110 is formed in the element formation layer102.

FIG. 12 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram toillustrate that part of a separate film 112 is removed from a heatrelease film 111.

FIG. 13 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram forillustrating a method for fixing the heat release film 111 to theelement formation layer 102.

FIG. 14 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram forillustrating a method for widening a gap 115 between the elementformation layer 102 and the release layer 101.

FIG. 15 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram forillustrating a method for supplying liquid 116 to the gap 115 betweenthe element formation layer 102 and the release layer 101.

FIG. 16 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram forillustrating a method for separating the element formation layer 102from the substrate 100 while the liquid 116 is being supplied.

FIG. 17 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is a diagram toillustrate that the element formation layer 102 is separated from thesubstrate 100.

FIG. 18 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is across-sectional view of the separated element formation layer 102 whichis held by the heat release film 111.

FIG. 19 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is across-sectional view of the semiconductor device.

FIG. 20 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 1 and is across-sectional view of the semiconductor device.

FIG. 21 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 2 and is a diagram forillustrating a method for supplying the liquid 116 in the gap 115between the element formation layer 102 and the release layer 101.

FIG. 22 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 2 and is a diagram forillustrating a method for supplying the liquid 116 in the gap 115between the element formation layer 102 and the release layer 101 whilethe element formation layer 102 is being peeled.

FIG. 23 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 3 and is a diagram forillustrating a method for supplying the liquid 116 in a gap between theelement formation layer 102 and the release layer 101.

FIG. 24 is a cross-sectional view for illustrating a method formanufacturing a semiconductor device of Example 3 and is a diagram forillustrating a method for supplying the liquid 116 in a gap between theelement formation layer 102 and the release layer 101 while the elementformation layer 102 is being peeled.

FIG. 25 is a cross-sectional view for illustrating a method for forminga release layer of Example 1.

FIG. 26 is a cross-sectional view for illustrating a method for formingan element formation layer of Example 1 and is a diagram to illustratethat an insulating film 103 of an element formation layer is formed overthe release layer 101.

FIG. 27 is a cross-sectional view for illustrating a method for formingan element formation layer of Example 1 and is a diagram to illustratethat an integrated circuit including a thin film transistor is formedover the insulating film 103.

FIG. 28 is a cross-sectional view for illustrating a method for formingan element formation layer of Example 1 and is a cross-sectional view ofthe element formation layer 102.

FIGS. 29A to 29D are diagrams each showing a structural example of asemiconductor device having an integrated circuit which can wirelesslycommunicate with an antenna.

FIGS. 30A and 30B are diagrams each showing a structural example of asemiconductor device of the present invention. FIG. 30A is a frontelevation of a liquid crystal module, and FIG. 30B is a cross-sectionalview of the liquid crystal module.

FIGS. 31A and 31B are diagrams each showing a structural example of asemiconductor device of the present invention. FIG. 31A is a frontelevation of an EL module, and FIG. 31B is a cross-sectional view of theEL module.

FIGS. 32A to 32C are diagrams each showing a structural example of asemiconductor device of the present invention. FIGS. 32A and 32B areoutside views of a television device, and FIG. 32C is an outside view ofan e-book reader.

FIG. 33 is a cross-sectional view showing a stacked structure of asample with which a peel test is performed.

FIG. 34 is a plan view of a sample with which a peel test is performed.

FIG. 35 is a graph showing a result of a peel test.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Mode

Hereinafter, embodiment mode and examples of the present invention willbe described with reference to the accompanying drawings. The sameelement is denoted with the same reference numeral and the redundantdescription is omitted. The present invention can be implemented invarious modes. As can be easily understood by a person skilled in theart, the modes and details of the present invention can be changed invarious ways without departing from the spirit and scope of the presentinvention. Thus, the present invention should not be interpreted asbeing limited to the following description of the embodiment mode andexamples.

When static electricity is generated on a surface of a layer (alsoincluding a substrate) formed of a high resistance substance, such as aninsulator, electric charge remains in a position where the electriccharge is generated if there is no path through which the electriccharge diffuses. When peeling proceeds and a potential due to thegenerated electric charge increases in this state, discharge occurs to apath through which electricity passes easily, for example, inside anelement formation layer.

Therefore, a method for manufacturing a semiconductor device of thepresent invention has a feature in which means that does not chargeelectric charge generated by peeling is provided. Specifically, when anelement formation layer is separated from a substrate, a surface whichappears by separating the element formation layer is wetted or moistenedby supplying liquid between two separated layers (there is the casewhere one layer is a substrate). The method for manufacturing thesemiconductor device of the present invention will be described withreference to FIGS. 1 to 7.

As shown in FIG. 1, the element formation layer 11 is formed over thesubstrate 10. The release layer 12 is formed over the substrate 10, andthe element formation layer 11 is formed over the release layer 12 sothat the element formation layer 11 can be easily separated from thesubstrate 10.

In the element formation layer 11, at least one semiconductor element isformed. For example, an integrated circuit formed of a thin filmtransistor, a diode, a resistor, a capacitor, or the like is formed inthe element formation layer 11. The element formation layer 11 is one ofcomponents of the semiconductor device.

The release layer 12 can be formed of metal- or alloy, for example.Metal is tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta),niobium (Nb), nickel (Ni), cobalt (Co), zirconium (Zr), zinc (Zn),ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir),or the like. Alloy is alloy of a plurality of metal elements selectedfrom these metal elements such as alloy of tungsten and molybdenum. Ametal film and an alloy film of the element can be formed by asputtering method. In addition, the thickness of the metal film or alloyfilm to serve as the release layer 12 may lie within the range of 20 nmto 100 nm.

In order to generate peeling preferentially between the elementformation layer 11 and the release layer 12, a surface of the metal filmor alloy film which is formed as the release layer 12 is oxidized. As amethod for oxidation, there are a thermal oxidation method, a method fortreating a surface with oxygen or N₂O plasma, a method for treating asurface with a solution having strong oxidizability, such as ozonewater, and the like. Another method is a method for forming an oxide atthe interface between the element formation layer 11 and the releaselayer 12 when the element formation layer 11 is formed. For example, inthe case where a silicon oxide is formed by a sputtering method, asurface of the metal film or alloy film can be oxidized when the siliconoxide is deposited on the surface of the metal film or alloy film. Notethat, instead of being oxidized the metal film or alloy film, the metalfilm or alloy film may be nitrided by plasma treatment or heattreatment.

In addition, the release layer 12 can be formed of a single layer or aplurality of layers. For example, the release layer 12 can be formed ofa multi-layer film having an insulating film formed of an inorganicmaterial such as a silicon oxide or a silicon oxynitride and a metalfilm (or an alloy film), so as not to generate peeling at the interfacebetween the substrate 10 and the release layer 12.

The substrate 10 is a substrate used for forming the element formationlayer 11 and the release layer 12 and is preferably a rigid body. Thesubstrate 10 is formed of, for example, a glass substrate, a quartzsubstrate, a metal substrate, a stainless steel substrate, a siliconwafer on which an insulating layer is formed, or the like.

After the element formation layer 11 is formed, as shown in FIG. 2, thesupport base material 13 is fixed on the element formation layer 11. Thesupport base material 13 is a member to facilitate handling of theelement formation layer 11 after separation from the substrate 10. Inaddition, the support base material 13 is also a member to facilitateoperation to transform the element formation layer 11 when the elementformation layer 11 is separated from the substrate 10.

In the case where the support base material 13 is not a member of asemiconductor device but is removed in a manufacturing process of thesemiconductor device, a base material capable of separation withoutdamaging the element formation layer 11 is used for the support basematerial 13. In addition, the support base material 13 preferably hasflexibility so as to transform the element formation layer 11.Therefore, a release film which can be peeled with weak force may beused for the support base material 13.

Note that, when the support base material 13 is used as the member ofthe semiconductor device, a plastic substrate and the like formed ofpolycarbonate, polyarylate, polyethersulfone, or the like are given. Inaddition, a flexible film (formed of polypropylene, polyester, vinyl,polyvinyl fluoride, polyvinyl chloride, or the like) is used as thesupport base material 13 and is attached to the element formation layer11 with an adhesive agent such as an epoxy resin in a structure of FIG.2.

As shown in FIG. 3, peeling is generated at the interface between theelement formation layer 11 and the release layer 12. Since peeling isgenerated, mechanical external force (so-called force in accordance witha law of classical mechanics) is provided to this interface. Forexample, as shown in FIG. 3, the element formation layer 11 istransformed by bending the support base material 13, so that peeling canbe generated at an end portion of the interface between the elementformation layer 11 and the release layer 12. Note that since it isdifficult to bend the release layer 12 because the substrate 10 is arigid body, the element formation layer 11 is transformed; however, therelease layer 12 may be transformed or both the element formation layer11 and the release layer 12 may be transformed, as long as the releaselayer 12 is easily transformed.

The mechanical external force which can transform the element formationlayer 11 can be applied by human hands or by pinching the support basematerial 13 with a holding device such as tweezers. In addition, theelement formation layer 11 can be transformed by twining the supportbase material 13 around a roller or the like to be described later.

As shown in FIG. 3, when peeling is generated at the end portion of theinterface between the element formation layer 11 and the release layer12, liquid 15 is supplied in a gap generated by peeling, and a lowersurface of the element formation layer 11 and the upper surface of therelease layer 12 which appear by peeling are wetted. Note that, when thesubstrate 10 comes on the bottom and the support base material 13 comeson the top, the lower surface means a surface of the layer on thesubstrate 10 side and the upper surface means a surface of the layer ona support base material 13 side.

In the present invention, as shown in FIG. 4, while the elementformation layer 11 is being peeled, the liquid 15 is supplied to a tipportion of peeling (a portion 17 surrounded with a chain line of FIG. 4)so that the lower surface of the element formation layer 11 and theupper surface of the release layer 12 which sequentially appear bypeeling are wetted with the liquid 15.

In the present invention, pure water can be used for the liquid 15.Although resistivity of pure water is 1 MΩ·cm or more, which is veryhigh, an impurity is mixed with pure water when pure water comes intocontact with the element formation layer 11 or the release layer 12, andelectrical resistance decreases. Therefore, by wetting the lower surfaceof the element formation layer 11 and the upper surface of the releaselayer 12 which appear by peeling with pure water, electric chargegenerated by peeling can be diffused on the lower surface of the elementformation layer 11 and the upper surface of the release layer 12.Accordingly, even when the surfaces of the element formation layer 11and the release layer 12 are formed of a high resistance material,discharge toward the inside of the element formation layer 11 and therelease layer 12 can be avoided.

That is, in the present invention, by supplying the liquid 15 to theportion where peeling is to be generated, a surface which appears bypeeling is wetted with the liquid, and electrical resistance of thesurface is reduced, at the same time as generation of peeling. Thus, inthe present invention, since electric charge due to peelingelectrification can be diffused at the moment when peeling is generated,discharge due to static electricity can be prevented.

In addition, as the liquid 15, an aqueous solution which has lowerresistivity than pure water can be used. The property of an aqueoussolution may be any of acid, alkaline, or neutral. For example, anaqueous solution in which acid or a base is dissolved, an aqueoussolution in which salt (salt may be any of acid salt, alkaline salt, andnormal salt) is dissolved, or the like can be used. As an aqueoussolution which can be used as the liquid 15, specifically, an aqueoussolution of carbon dioxide (CO₂), an aqueous solution (hydrochloricacid) of hydrogen chloride (HCl), an aqueous solution oftetramethylammonium hydroxide, an aqueous solution of ammonium chloride(NH₄Cl), and the like are given as examples.

As the liquid 15, it is preferable to use an aqueous solution in whichmolecules that become gas at normal temperature (25° C.) underatmospheric pressure are dissolved in water, such as an aqueous solutionof carbon dioxide or an aqueous solution of hydrogen chloride. This isbecause the molecules which are dissolved with water become gas and doesnot remain when the liquid 15 is dried. In addition, when an aqueoussolution in which salt is dissolved is used, it is preferable to usesalt which functions as a surfactant, because a surface can be easilywetted with the liquid 15 when the surfactant is dissolved.

In addition, a mixed solution of water and volatile liquid can also beused as the liquid 15. By containing volatile liquid in the liquid 15,drying treatment can be omitted. As long as volatile liquid contains atleast about 0.1% water, electric charge can be diffused by the liquid15, that is, an antistatic effect can be obtained. Since some organicsolvent such as commercial high-purity ethanol or acetone contains waterat a concentration of 0.1% or more as an impurity, such a commercialorganic solvent can be used as a mixed solution of water and volatileliquid of the present invention, without controlling the concentration.In addition, in order to take advantage of volatile liquid, theconcentration of the volatile liquid is preferably 30% or more.Accordingly, a low purity organic solvent, such as denatured ethanolwhich is widespread as an organic solvent can also be used as the mixedsolution of water and volatile liquid of the present invention, withoutcontrolling the concentration.

As shown in FIG. 5, when peeling between the element formation layer 11and the release layer 12 is completed, the substrate 10 with the releaselayer 12 is peeled from the element formation layer 11. As shown in FIG.6, the first flexible substrate 18 is fixed to the lower surface of theelement formation layer 11 with an adhesive agent. Next, the supportbase material 13 is peeled from the upper surface of the elementformation layer 11. When the support base material 13 is peeled, theliquid 15 may be supplied between the element formation layer 11 and thesupport base material 13, in a similar manner that the liquid 15 issupplied between the element formation layer 11 and the release layer12, in the case where the element formation layer 11 might be destroyedby peeling electrification.

Next, as shown in FIG. 7, a second flexible substrate 19 is fixed to theupper surface of the element formation layer 11. The second flexiblesubstrate 19 may be provided, as necessary. By the above-describedmanufacturing method, a flexible semiconductor device having the elementformation layer 11 shown in FIG. 7 can be manufactured.

The first flexible substrate 18 and the second flexible substrate 19each are a base material which can be bent or curved. As these flexiblesubstrates 18 and 19, a plastic substrate formed of polycarbonate,polyarylate, polyethersulfone, or the like can be used, for example. Inaddition, a film formed of an organic compound such as polyethyleneterephthalate, polypropylene, polyester, vinyl, polyvinyl fluoride, orpolyvinyl chloride can be used.

The first flexible substrate 18 and the second flexible substrate 19 arefixed to the element formation layer 11 by using an adhesive agent inwhich adhesiveness is developed by heating or irradiation with visiblelight or ultraviolet light, and after cooling, the adhesive agent iscured to attach an object. For example, a resin such as a thermoplasticresin or a photopolymerizable resin can be used as an adhesive agent.

In the present invention, the liquid 15 is sequentially supplied to thetip portion of peeling which is surrounded with the chain line of FIG. 4(the portion 17 surrounded with the chain line of FIG. 4). In otherwords, the liquid may be supplied to a surface which sequentiallyappears by peeling. One method for supplying liquid is a method fordropping or pouring the liquid 15 in a gap generated by peeling withinjection means such as a nozzle or a dropper. In this case, the liquid15 may always be supplied from start to end of peeling or may besupplied intermittently. In addition, when the liquid 15 is poured ordropped only at an early stage of peeling as shown in FIG. 3, thesupplied liquid 15 can be spread to the tip portion of peeling (theportion 17 surrounded with the chain line of FIG. 4) due to a capillaryphenomenon, as peeling proceeds.

Another method for supplying the liquid 15 is a method for spraying theliquid 15 in an atomized form with spray means such as a spray nozzle ora sprayer. By this method, while peeling proceeds, the liquid 15 mayalways be sprayed, may be sprayed intermittently, or may be sprayed onlyat an early stage of peeling. Note that when pure water is used as theliquid 15, the liquid 15 in the form of moisture can be sprayed.

Another method for supplying the liquid 15 is a method in which a liquidhold medium that can absorb liquid and release the liquid by applyingexternal force, such as sponge or cloth, is used.

In addition, another method for supplying the liquid 15 is a method inwhich the liquid 15 is put in a container and the element formationlayer 11 is separated from the substrate 10 while the substrate 10 isbeing immersed in the liquid 15. In this case, a portion where peelingproceeds is immersed in the liquid 15, so that the liquid 15 can bespread to the tip portion of peeling (the portion 17 surrounded with thechain line of FIG. 4).

Here, a method for supplying the liquid 15 by using a liquid hold mediumwill be described with reference to cross-sectional views shown in FIGS.1 to 4, 8, and 9. Note that another supplying method will be describedin detail in the following example.

By performing the steps shown in FIGS. 1 and 2, the release layer 12 andthe element formation layer 11 are formed over the substrate 10, and thesupport base material 13 is fixed on the element formation layer 11. Asshown in FIG. 3, by bending the support base material 13, peeling isgenerated at the interface between the element formation layer 11 andthe release layer 12.

Next, as shown in FIG. 8, liquid holding means 21 containing the liquid15 is inserted in a gap generated by peeling. Note that, after theliquid holding means 21 is inserted in the gap, the liquid 15 may besupplied with a chopper or a nozzle, and the liquid holding means 21 maycontain the liquid 15. As the liquid holding means 21, one having afunction to absorb liquid such as sponge or cloth can be used.

In FIG. 8, as for the size of the liquid holding means 21, it isdesirable that the length in a direction perpendicular to paper belonger than the length of one side of the substrate 10 in this directionand an end portion of the liquid holding means 21 not be over thesubstrate 10.

Furthermore, peeling proceeds by applying mechanical force to theinterface between the element formation layer 11 and the release layer12 through the support base material 13. As an example of a method forapplying mechanical force, a method for winding the element formationlayer 11 by using a roller 22 will be described. As shown in FIG. 9, theroller 22 is rolled on the support base material 13 and the elementformation layer 11 with the support base material 13 is wound, so thatthe element formation layer 11 can be separated from the substrate 10.

When the roller 22 passes over the liquid holding means 21, the liquid15 contained in the liquid holding means 21 is pushed out due to theself-weight of the roller 22, and a portion to be peeled comes intocontact with the liquid 15. That is, the upper surface of the releaselayer 12 and the lower surface of the element formation layer 11 whichappear as the roller 22 is rotated can be wetted sequentially with theliquid 15. Therefore, electric charge generated by peeling can bediffused by the liquid 15 at the moment when peeling is generated, andelectric charge can be prevented.

The method for manufacturing the semiconductor device of the presentinvention is described using the case where the release layer 12 is themetal film or the alloy film, as an example. However, the presentinvention is not limited to this example. A release layer may be formedof a material so that an element formation layer can be peeled byapplying mechanical force.

The method for manufacturing the semiconductor device of the presentinvention is described using the case where peeling is generated at theinterface between the element formation layer 11 and the release layer12, as an example. However, a portion where peeling is generated is notlimited thereto. For example, as the release layer 12, an amorphoussilicon film containing hydrogen is formed using silane gas as a rawmaterial over the substrate 10 by a plasma CVD method. A laser beam inthe ultraviolet region, such as an excimer laser beam is emitted fromthe substrate 10 side, and hydrogen is released from the amorphoussilicon film. Thus, adhesion of the amorphous silicon film and thesubstrate 10 decreases, or the amorphous silicon film itself becomesfragile; therefore, peeling can be generated at the interface betweenthe release layer 12 and the substrate 10 or inside the release layer12.

In addition, by providing the release layer 12 as a multi-layer ofdifferent materials, peeling can also be generated at an interface of alayer which forms a release layer. For example, as the release layer 12,a tungsten film is formed by a sputtering method, and a silicon dioxidefilm is formed over the tungsten film by a sputtering method. When thesilicon dioxide film is deposited, a tungsten oxide is generated at aninterface between the tungsten film and the silicon dioxide film.Accordingly, since junction at the interface between the tungsten filmand the silicon dioxide film is weak, peeling can be generated betweenthe tungsten film and the silicon dioxide film, by applying force to therelease layer 12.

Example 1

In this example, a method for manufacturing a semiconductor devicecapable of inputting and outputting data by noncontact, to which thepresent invention is applied, will be described. In this example, anelement formation layer was provided with an integrated circuit whichperforms wireless communication using a 13.56 MHz signal and functionsas an IC tag. This example will be described with reference to FIGS. 10to 20, and 25 to 28.

As shown in FIG. 10, the release layer 101 was formed over the substrate100, and an integrated circuit was formed over the release layer 101. Amethod for manufacturing the release layer 101 and the element formationlayer 102 will be described with reference to FIGS. 25 to 28.

As the substrate 100, a substrate in which a glass substrate (athickness of 0.7 mm, product name: AN100) made by Asahi Glass Co., Ltd.was cut to 5 inches on each side was used. As shown in FIG. 25, therelease layer 101 had a multi-layer structure of a silicon oxynitride(SiO_(x)N_(y), x<y) layer 101 a and a tungsten layer 101 b. The siliconoxynitride layer 101 a was formed to have a thickness of 200 nm by usingSiH₄ and N₂O as source gas with a parallel plate plasma CVD apparatus.The tungsten layer 101 b was formed to have a thickness of 50 nm byusing a tungsten target with a sputtering apparatus. By generating N₂Oplasma, a surface of the tungsten layer 101 b was subjected to plasmatreatment and oxidized, and then a tungsten oxide was formed. With thisplasma treatment, peeling comes to be generated at the tungsten oxidewhich is the interface between the release layer 101 and the elementformation layer 102. In addition, when the tungsten layer 101 b wasformed by a sputtering method, the silicon oxynitride layer 101 a whichwas a lower layer of the release layer 101 was a barrier layer for notdiffusing an impurity from the substrate 100 (e.g., a glass substrate).As the barrier layer, an insulating film formed of another inorganicmaterial such as silicon oxide or silicon nitride can be used.

As shown in FIG. 26, the insulating film 103 to serve as a baseinsulating layer of a semiconductor element such as a TFT of the elementformation layer 102 was formed over the release layer 101. Theinsulating film 103 had a stacked structure of a silicon oxynitride(SiO_(x)N_(y), x<y) layer 103 a and a silicon oxynitride (SiO_(x)N_(y),x>y) layer 103 b. The first silicon oxynitride layer 103 a was formed byusing SiH₄, N₂O, NH₃, and H₂ as source gas with a parallel plate plasmaCVD apparatus. The second silicon oxynitride layer 103 b was formed byusing SiH₄ and N₂O as source gas with a parallel plate plasma CVDapparatus.

As shown in FIG. 27, an integrated circuit was formed of a semiconductorelement such as a TFT or a capacitor over the insulating film 103. InFIG. 27, as a cross-sectional view of the integrated circuit, only aCMOS circuit formed of an n-channel TFT 104 and a p-channel TFT 105 wasillustrated. Note that 48 (8 rows×6 columns) integrated circuits whichwere arranged in matrix were formed over one substrate 100 at the sametime.

An antenna 106 connected to the integrated circuit (the TFTs 104 and105) was formed for wireless communication. First, before the antenna106 was formed, an insulating film 107 was formed to cover theintegrated circuit (the TFTs 104 and 105). In this example, theinsulating film 107 was formed of photosensitive polyimide, and anopening for connecting the antenna 106 was formed in the insulating film107.

Over the insulating film 107, a silver (Ag) paste was formed into adesired shape by a printing method, and the antenna 106 was formed. Notethat, of 48 integrated circuits formed over the substrate 100, half ofthem were provided with the antenna 106, and a stack of the integratedcircuit and the antenna was formed. In addition, the other half of themwere provided with a bump for connecting an external antenna by using asilver paste, instead of the antenna 106. Note that the antenna 106 andthe bump can be formed in such a way that a conductive film such asaluminum is formed by a sputtering method and processed into a desiredshape by an etching method.

Lastly, a resin layer 108 for sealing was formed to cover the antenna106, as shown in FIG. 28. As the resin layer 108, an epoxy resin layerhaving a thickness of 30 μm was formed. As described above, a structuralobject formed of the release layer 101 and the element formation layer102 was formed over the substrate 100.

A plurality of integrated circuits is formed in the element formationlayer 102 over the substrate 100. When the element formation layer 102was separated from the substrate 100, a groove 110 is formed in theelement formation layer 102 in advance as shown in FIG. 11, so thatintegrated circuits can be separated from one another. The groove 110 isformed so as to surround the periphery of each integrated circuit in theelement formation layer 102. In this example, the groove 110 was formedby emitting a UV laser beam having a wavelength of 266 nm and an outputof 2 W.

By forming the groove 110 in the element formation layer 102, peelingwas slightly generated at the interface between the element formationlayer 102 and the release layer 101 which were exposed by the groove110, which led to a state that the element formation layer 102 floatedalong the groove 110.

A heat release film to serve as a support base material is prepared inpeeling. The heat release film 111 is a 100-μm-thick film formed ofpolyethylene terephthalate, and one surface of the film is provided witha thermosetting resin layer having a thickness of 50 μm. Thethermosetting resin layer functions as an adhesive layer before heatcuring, and the surface of the thermosetting resin layer is protectedwith the separate film 112. In order to fix the heat release film 111 tothe element formation layer 102 by using the thermosetting resin layer,part of the separate film 112 was removed, as shown in FIG. 12.Accordingly, the separate film 112 was irradiated with a UV laser beam,and a cut similar to the groove 110 formed in the element formationlayer 102 was made, so that the separate film 112 inside the cut waspeeled.

The heat release film 111 is attached to the upper surface of theelement formation layer 102. As shown in FIG. 13, by using a commerciallaminator provided with a pair of rollers 114, the heat release film 111was attached to the element formation layer 102. The heat release film111 is attached to a portion (a portion to serve as an object ofpeeling) of the element formation layer 102 to form a semiconductordevice eventually, by using the thermosetting resin layer (adhesivelayer). On the other hand, the heat release film 111 is not attached toa portion (a portion which does not serve as a separation object) wherethe semiconductor device is not formed because the separate film 112remains.

At the periphery of the groove 110, there is a state that the elementformation layer 102 is floated slightly from the release layer 101, whenpeeling is generated. In the case where a gap between the elementformation layer 102 and the release layer 101, into which liquid isdropped, is small, the gap is widened. In this example, plastic tweezerswere inserted into the peeled lower surface of the element formationlayer 102, and as shown in FIG. 14, the gap 115 was generated between anupper surface of the release layer 101 and the lower surface of theelement formation layer 102.

As shown in FIG. 15, the liquid 116 is dropped into the gap 115 betweenthe release layer 101 and the element formation layer 102. In thisexample, the liquid 116 was dropped with a dropper 117. A sufficientamount of the liquid 116 to be diffused into the gap 115 was poured. Inthe following step, the liquid 116 is not supplied.

In addition, as the liquid 116, pure water, pure water in which CO₂ isdissolved (hereinafter referred to as “CO₂ water”), pure water in whichhydrogen chloride is dissolved (hereinafter referred to as “HCl water”),and ethanol were used. Note that an aqueous solution having resistivityof 0.2 MΩ·cm was used as CO₂ water. An aqueous solution having ahydrogen chloride concentration of 180 ppm was used as HCl water. Acommercial ethanol having an ethanol concentration of 99.5% and a waterconcentration of 0.5% was used without controlling concentration.

As shown in FIG. 16, when a non-conductive roller 118 was rolled on theheat release film 111, the element formation layer 102 with the heatrelease film 111 was twined around the roller 118 and the elementformation layer 102 was separated from the substrate 100. When theroller 118 is rotated, the element formation layer 102 is peeledsequentially from the release layer 101, and the liquid 116 supplied inthe state shown in FIG. 15 moves to a portion 119 (a tip portion ofpeeling) where the element formation layer 102 is to be peeled, by usinga capillary phenomenon. Therefore, the lower surface of the elementformation layer 102 and the upper surface of the release layer 101 whichappeared by peeling were able to be wetted with the liquid 116, at themoment when peeling was generated.

Next, as shown in FIG. 17, the element formation layer 102 and the heatrelease film 111 which was coherent to the roller 118 were peeled. Asshown in FIG. 18, the element formation layer 102 provided with the heatrelease film 111, which is separated from the substrate 100 can beobtained. In the case where pure water, CO) water, and HCl water wereused as the liquid 116, the heat release film 111 and the elementformation layer 102 were dried by using an air blow device.

When the heat release film 111 is peeled from the roller 118 (see FIG.17), the liquid 116 may be supplied between the roller 118 and the heatrelease film 111. In this example, it is confirmed that the elementformation layer 102 can be peeled from the roller 118 without destroyingthe element formation layer 102, even when the liquid 116 is not poured.One of the reasons why the element formation layer 102 is not destroyedis that the insulating film 107 formed of an epoxy resin having athickness of 30 μm is provided between the integrated circuit and theheat release film 111 in the element formation layer 102.

When the element formation layer 102 was observed by an opticalmicroscope in a state of being provided with the heat release film 111(a state of FIG. 18), it was checked whether power breakdown due todischarge (destruction in which a semiconductor layer, an insulatingfilm, a conductive film, or the like is melted due to heat generated bydischarge) was generated. An object of the observation with the opticalmicroscope is to check whether visible destruction is not generated inthe semiconductor element. In this example, all 48 integrated circuitsformed over one substrate 100 were observed by the optical microscope.

Pure water, CO₂ water, HCl water, and ethanol were used as the liquid116; however, as a result of the observation with the opticalmicroscope, power breakdown was not generated in the integrated circuit,even with any of the liquid 116. On the other hand, when the elementformation layer 102 was separated from the substrate 100 without supplyof the liquid 116, there was an integrated circuit in which powerbreakdown was generated.

TABLE 1 Results of observations of integrated circuits in the elementformation layer with the optical microscope. Total number PercentagesNumber of Total number of of destroyed of destroyed Kind of observedobserved integrated integrated liquid substrates integrated circuitscircuits circuits Pure water 3 144 0 0.0% CO₂ water 3 144 0 0.0% HClwater 1 48 0 0.0% Without 4 192 59 30.7% liquid

Table 1 summarizes observations with the optical microscope. Table 1shows observations of a substrate (a sample) to which the liquid 116 wassupplied and a substrate (a sample) to which the liquid 116 was notsupplied. As the liquid 116, pure water, CO₂ water, and HCl water wereused. As shown in Table 1, when the liquid 116 was not supplied,destruction capable of being seen by appearance such as disconnection orfilm fusion was observed in 30% or more of integrated circuits. Inaddition, regularity was not found in distribution (a position formedwith the substrate) of the integrated circuit in which destruction wasgenerated over the substrate. Therefore, as for the substrate to whichliquid is not supplied, a defective might be overlooked by samplinginspection. However, total inspection has a large burden in terms ofcost or cycle time. By implementing the present invention, powerbreakdown due to peeling discharge can be prevented; therefore, theburden of inspection can be reduced.

After the state of FIG. 18 is obtained, a laminate film 121 which is aflexible substrate is attached to the lower surface of the elementformation layer 102. After the resin layer is cured by heating the heatrelease film 111 to lose the adhesiveness of the resin layer, the heatrelease film 111 is peeled from the upper surface of the elementformation layer 102. The element formation layer 102 with the laminatefilm 121 is divided into each integrated circuit. Another laminate film122 is attached to the upper surface of the divided element formationlayer 102. By heating while pressurizing, as shown in FIG. 19, asemiconductor device having the element formation layer 102 sealed withtwo laminate films 121 and 122 is manufactured.

Note that, as shown in FIG. 20, a film 123 provided with an antenna isfixed to the element formation layer 102 including the circuit of theintegrated circuits which is not connected to an antenna, instead of thelaminate film 122, and a semiconductor device was manufactured. Ananisotropic conductive adhesive is used to attach the film 123 and theelement formation layer 102 to each other, and a terminal of the antennaover the film 123 is electrically connected to the bump of theintegrated circuit.

The semiconductor devices shown in FIGS. 19 and 20 can be used as aninlet (also referred to as an inlay) incorporated in a non-contact ICtag or the like. Note that the semiconductor device of the presentinvention includes not only an intermediate product such as an inlet,but also an end product such as an IC card, an ID label, and an IC tagin which an inlet as shown in FIGS. 19 and 20 is incorporated in aplastic card, attached to a sticker label, or embedded in paper.

It was examined whether a predetermined operation was performed byinputting a signal wirelessly in the semiconductor device which has beencompleted through a manufacturing method of this example, shown in FIGS.19 and 20. It was confirmed that all semiconductor devices(semiconductor devices including the integrated circuit which was anobservation object by the optical microscope) which were observed by theoptical microscope were operated. In consideration of the result of theobservation with the optical microscope in Table 1, it is thought thatstatic electricity generated by peeling was able to be prevented frombeing discharged when the element formation layer was separated from thesubstrate while liquid was being supplied. That is, by implementing thepresent invention, it was found that the semiconductor element includedin the semiconductor device can be prevented from being destroyed andcharacteristics of the semiconductor element can be prevented from beingdeteriorated due to electric charge generated by peeling.

Note that in the structure of this example, the lower surface of theelement formation layer 102 which appears by peeling is formed of atungsten oxide or a silicon oxynitride and is a high resistive material;however, an integrated circuit can be prevented from being destroyed dueto peeling discharge, by using this example. Therefore, by using thepresent invention, a material which forms the lower surface of theelement formation layer 102 is not limited to a conductive material andcan be formed of an insulating material. As described above, with thepresent invention, electric charge generated by peeling can be preventedfrom being discharged into both inside of two separated layers;therefore, even when the lower surface of the element formation layer isformed of an insulating material, the semiconductor element included inthe element formation layer can be prevented from being destroyed andcharacteristics of the semiconductor element can be prevented from beingdeteriorated, due to static electricity generated by peeling.

In addition, when the element formation layer 102 is bent, the elementformation layer 102 is separated from the substrate. An external forceis applied to the element formation layer 102 by bending the elementformation layer 102, and as a result of this, the element formationlayer 102 may be broken or cracked in some case. It is found thatdestruction (crack or breaking) due to transformation of the elementformation layer 102 is hardly generated by supplying liquid andseparating the element formation layer 102 from the substrate 100 as thepresent invention.

TABLE 2 Observation results of element formation layers with opticalmicroscope. Total number Total number of Percentages of Number ofobserved element formation element formation of element layers in whichlayers in which Kind of observed formation breaking and the breaking andthe liquid substrates layers like are observed like are occurred CO₂ 296 4 4.2% water Without 2 96 53 55.2% liquid

Table 2 shows results of observation on whether the element formationlayer 102 has a crack or breaking in the state of FIG. 18, by using theoptical microscope. Table 2 shows observations of a substrate (a sample)in which CO₂ water is used for the liquid 116 and a substrate (a sample)to which the liquid 116 is not supplied, by using the opticalmicroscope. It is found that about half the number of the elementformation layers which are peeled without supply of liquid generatesbreaking or cracks; however, the generation of breaking or a crack canbe reduced to about 4% by pouring CO₂ water.

Therefore, when the element formation layer is separated from thesubstrate while liquid is being supplied, destruction or characteristicdeterioration of the semiconductor element due to static electricitythat is generated by peeling can be prevented, and generation ofdestruction (breaking or a crack) of the element formation layer due totransformation can be suppressed.

Example 2

In this example, a method for supplying the liquid 116, which isdifferent from that described in Example 1, will be described. In thisexample, a method for spraying the liquid 116 in an atomized form isdescribed and description of a common portion to that in Example 1 isomitted.

Similarly to Example 1, steps which have been described with referenceto FIGS. 10 to 13 are performed. Next, in Example 1, the plastictweezers were inserted into the peeled lower surface of the elementformation layer 102, and the gap 115 was generated between the uppersurface of the release layer 101 and the lower surface of the elementformation layer 102, as shown in FIG. 14. In this example, this step isunnecessary.

Next, the roller 118 is rolled on the heat release film 111 similarly toExample 1, and the element formation layer 102 with the heat releasefilm 111 is peeled from the release layer 101. When the roller 118 isrolled, the liquid 116 in an atomized form was sprayed from spray means130 into a gap between the element formation layer 102 and the releaselayer 101 from a side where the roller 118 starts rolling, as shown inFIG. 21. The liquid 116 is sprayed so as to wet a portion where peelingis generated by rotating the roller 118.

As shown in FIG. 22, while the roller 118 is being rotated, the liquid116 is sprayed from the spray means 130 so as to wet the portion wherepeeling is generated. With the roller 118, the element formation layer102 with the heat release film 111 is separated from the substrate 100.Next, a stack of the heat release film 111 and the element formationlayer 102 is peeled from the roller 118 and fixed to the heat releasefilm 111 as shown in FIG. 18, so that the element formation layer 102which is divided into each semiconductor device is obtained.

By the method of this example, the steps up to and including the stepsin FIG. 18 were performed by using CO₂ water which was the sameconcentration as that in Example 1, as the liquid 116. Except that amethod for supplying liquid was different, the same steps were performedby using the same means as that in Example 1. Note that, in thisexample, CO₂ water was sprayed by a sprayer.

In this example, similarly to Example 1, it was examined whether thereis power breakdown due to discharge by observing the element formationlayer 102 by the optical microscope in the state of FIG. 18. Theobservation with the optical microscope was conducted on all integratedcircuits formed by using the same substrate 100. In this example, therewas no integrated circuit in which power breakdown was generated.

In the element formation layer 102 observed by the optical microscope,similarly to Example 1, it was examined whether the semiconductor deviceperformed a predetermined operation by manufacturing the semiconductordevice shown in FIG. 19 or FIG. 20 and inputting a signal wirelessly. Itwas confirmed that all semiconductor devices operated. Therefore,similarly to Example 1, it was confirmed that, by the method of thisexample, static electricity generated by peeling was able to beprevented from being discharged when the element formation layer wasseparated from the substrate while liquid was being supplied.

In this example, since a step of expanding the gap 115 between the uppersurface of the release layer 101 and the lower surface of the elementformation layer 102 shown in FIG. 14 is unnecessary, automation of apeeling step is easier than that of the method of Example 1.

Example 3

In this example, a method for supplying the liquid 116, which isdifferent from those described in Example 1 and Example 2, will bedescribed. Description of a common portion to that in Example 1 isomitted. In this example, a method for supplying liquid by separatingthe element formation layer 102 from a substrate while the substrate isbeing immersed in the liquid 116 is described.

Similarly to Example 1, steps described with reference to FIGS. 10 to 14are performed. Next, as shown in FIG. 23, a container 140 which containsthe liquid 116 is prepared. In the container 140, the substrate 100, therelease layer 101, and the element formation layer 102 are immersed inthe liquid 116. The substrate 100 is put in the container 140 so thatthe heat release film 111 comes on the top.

In this state, as shown in FIG. 24, the roller 118 is rolled on the heatrelease film 111, and the element formation layer 102 with the heatrelease film 111 is peeled from the release layer 101. Since the releaselayer 101 is peeled from the element formation layer 102 in the liquid116, a surface where peeling is generated can always be immersed in theliquid 116. It is preferable to adjust the amount of the liquid 116 inthe container 140 so as not to immerse the heat release film 111 in theliquid 116. This is because, when the heat release film 111 touches theliquid 116, the heat release film 111 is hard to be attached to theroller 118.

Next, the stack of the heat release film 111 and the element formationlayer 102 is peeled from the roller 118 and fixed to the heat releasefilm 111 as shown in FIG. 18, so that the separated element formationlayer 102 is obtained.

By the method of this example, the steps up to and including the stepsin FIG. 18 were performed by using CO₂ water which was the sameconcentration as that in Example 1, as the liquid 116. Except that amethod for supplying liquid was different, the same steps were performedby using the same means as that in Example 1.

In this example, similarly to Example 1, it was checked whether powerbreakdown due to discharge existed by observing the element formationlayer 102 by the optical microscope in the state of FIG. 18. Theobservation with the optical microscope was conducted on all integratedcircuits formed over one substrate 100. In this example, there was nointegrated circuit in which power breakdown was generated, as well.

In the element formation layer 102 observed by the optical microscope,similarly to Example 1, it was examined whether the semiconductor deviceoperated by manufacturing the semiconductor device shown in FIG. 19 orFIG. 20 and inputting a signal wirelessly. It was confirmed that allsemiconductor devices operated. Therefore, similarly to Example 1, itwas confirmed that, by the method of this example, static electricitygenerated by peeling was able to be prevented from being discharged whenthe element formation layer was separated from the substrate whileliquid was being supplied.

Note that in this example, it is necessary to pay attention to the depthof the liquid 116 in the container 140. It was desirable that the depthof the liquid 116 be almost the same height as the thickness of thesubstrate 100. When the depth of the liquid 116 is deep, there is apossibility that the upper surface of the heat release film 111 iswetted and the heat release film 111 is not attached to the roller 118.On the other hand, when the depth of the liquid 116 is extremelyshallow, there is a possibility that the liquid 116 does not enter a gapbetween the release layer 101 and the element formation layer 102. In astate of FIG. 23, when the substrate 100 was put in the container 140,it can be visually confirmed that the liquid 116 enters the gap betweenthe release layer 101 and the element formation layer 102. By checkingwhether the liquid 116 enters, the amount of the liquid 116 iscontrolled.

As described in Examples 1 to 3, when the element formation layer isseparated from the substrate while liquid is being supplied, destructionor characteristic deterioration of the semiconductor element due tostatic electricity that is generated by peeling can be prevented.Further, generation of destruction such as breaking or a crack generatedby applying mechanical external force in the element formation layer canbe reduced.

Example 4

In this example, a structural example of a semiconductor device havingan integrated circuit which can communicate with an antenna wirelesslywill be described with reference to FIGS. 29A to 29D.

FIG. 29A shows a structural example of an ID label as a semiconductordevice of the present invention. A plurality of ID labels 161 is formedon a label board 160 (separate sheet). Each ID label 161 contains aninlet (also referred to as an inlay) 162 having an antenna which cancommunicate wirelessly and an integrated circuit. The ID labels 161 areput in a box 163. In addition, information on the product and service(e.g., a product name, a brand name, a trademark, an owner of thetrademark, a seller, a manufacturer, or the like) are written on the IDlabels 161. On the other hand, an ID number which is peculiar to theproduct (or a kind of the product) is stored in the integrated circuitincorporated in the inlet 162. Much information which cannot be writtenon a surface of the ID label 161, such as an production area, a sellingarea, quality, a raw material, efficacy, a use application, quantity,the shape, price, a production method, usage, a production time, a usagetime, an expiration date, an instruction of the product, or informationon intellectual properties of the product can be stored in theintegrated circuit of the inlet 162.

FIG. 29B shows a structural example of an ID tag 165. In the ID tag 165,the inlet 162 is incorporated in a paper tag or a plastic tag. Byproviding the ID tag 165 which can communicate wirelessly to a product,product management becomes easy. For example, when the product isstolen, the criminal can be quickly recognized by tracing a path of theproduct. By providing the ID tag in this manner, a product havingexcellent so-called traceability can be distributed.

FIG. 29C shows a structural example of an ID card 166. The ID card 166has a structure in which the inlet 162 (not shown) is interposed betweentwo plastic cards. As such an ID card 166, any of cards such as a cashcard, a credit card, a prepaid card, an electronic ticket, electronicmoney, a telephone card, and a membership card is given as an example.

FIG. 29D shows a structural example of a semiconductor device in whichpaper contains an integrated circuit and an example in which the presentinvention is used for a bearer bond 167. The inlet 162 is embedded inthe bearer bond 167. Note that although a stamp, tickets such as aticket and a platform ticket, an admission ticket, a gift certificate, abook coupon, a stationary coupon, a beer coupon, a rice coupon, variouskinds of gift coupons, various kinds of service ticket, and the like areincluded in the bearer bond 167, needless to say, the present inventionis not limited to these.

Example 5

In this example, a structural example of an active matrix liquid crystalmodule as a semiconductor device of the present invention will bedescribed with reference to FIGS. 30A and 30B. FIG. 30A is a frontelevation showing a liquid crystal module, and FIG. 30B is across-sectional view cutting along a line A-A′ in FIG. 30A.

Reference numeral 200 denotes a first flexible substrate; 201 shown by adotted line denotes a signal line driver circuit; 202 denotes a pixelportion; and 203 denotes a scan line driver circuit. Over the firstflexible substrate 200, the pixel portion 202 formed of a thin filmtransistor or the like, the signal line driver circuit 201, and the scanline driver circuit 203 are formed in an element formation layer 190. Byfixing the element formation layer 190 to the first flexible substrate200 with an adhesive agent, a liquid crystal module substrate is formed.The liquid crystal module substrate is manufactured by any of themethods described in the above-described embodiment mode and Examples 1to 4.

Next, the cross-sectional structure of the element formation layer 190will be descried with reference to FIG. 30B. In the element formationlayer 190, a semiconductor element is formed over a base film 209 formedof an insulating film. The signal line driver circuit 201 includes aCMOS circuit formed in a combination of an n-channel thin filmtransistor 211 and a p-channel thin film transistor 212. The pixelportion 202 includes a switching thin film transistor 213 and acapacitor 214. The switching thin film transistor 213 is covered with aninterlayer insulating film 221. A pixel electrode 222 is formed over theinterlayer insulating film 221. The pixel electrode 222 is electricallyconnected to the switching thin film transistor 213.

A protective film 223 is formed so as to cover a wiring of the switchingthin film transistor 213, the pixel electrode 222, wirings of then-channel thin film transistor 211 and the p-channel thin filmtransistor 212. By the protective film 223, an impurity can be preventedfrom entering an active layer of the thin film transistor, theinterlayer insulating film 221, and the like. An orientation film 224 isformed over the protective film 223. Note that the orientation film 224is formed, as necessary.

A wiring 210 in the element formation layer 190 is a wiring fortransmitting a signal or the like to be inputted to the signal linedriver circuit 201 and the scan line driver circuit 203, and isconnected to an FPC (Flexible Printed Circuit) 208 to serve as anexternal input terminal. Note that the liquid crystal module of thepresent invention includes both of a mode in which only the FPC 208 isprovided and a mode in which both the FPC 208 and a PWB (Printed WiringBoard) are provided.

The liquid crystal module of this example includes the liquid crystalmodule substrate having the first flexible substrate 200 and the elementformation layer 190, the counter substrate in which a second flexiblesubstrate 230 is a base material, a sealant 205, liquid crystal 240, andthe FPC (Flexible Printed Circuit) 208. The liquid crystal module ofthis example can be bent.

The counter substrate is provided with a color filter 231, a blackmatrix (BM) 232, an opposite electrode 233, and an orientation film 234which are formed on the second flexible substrate 230. The color filter231 can be provided on a first flexible substrate 200 side. In addition,a liquid crystal module of an IPS system can be formed by providing theopposite electrode 233 in the element formation layer 190 of the firstflexible substrate 200.

Facing the first flexible substrate 200, the second flexible substrate230 is fixed to the first flexible substrate 200 with the sealant 205,and the liquid crystal 240 is injected between the first flexiblesubstrate 200 and the second flexible substrate 230 and sealed with thesealant 205.

In this example, the example in which the signal line driver circuit 201and the scan line driver circuit 203 are formed in the element formationlayer 190 is shown; however, only the pixel portion 202 is formed in theelement formation layer 190, the signal line driver circuit 201 and thescan line driver circuit 203 which are formed of an IC chip using asilicon wafer can be electrically connected to the pixel portion 202over the first flexible substrate 200 by a COG method or a TAB method.

Example 6

In this example, a structural example of an active matrix EL module willbe described as a semiconductor device of the present invention, withreference to FIGS. 31A and 31B. FIG. 31A is a front elevation of the ELmodule, and FIG. 31B is a cross-sectional view cutting along a line A-A′of FIG. 31A.

The EL module shown in FIGS. 31A and 31B can be bent, and has astructure in which a transistor and a light-emitting element which areformed in an element formation layer are sealed with a sealant 305formed between a first flexible substrate 301 and a second flexiblesubstrate 306.

Over the first flexible substrate 301, an element formation layer 300including a pixel portion 302, a signal line driver circuit 303, and ascan line driver circuit 304 is fixed with an adhesive agent, and asubstrate for an EL module is formed. The substrate for the EL module isformed by any of the methods described in embodiment mode and Examples 1to 4.

The EL module is formed by sealing the substrate for the EL module andthe second flexible substrate 306 with the sealant 305. In the EL moduleof this example, a space sealed with the substrate for the EL module,the sealant 305, and the second flexible substrate 306 is filled with afiller 307. As the filler 307, an ultraviolet curable resin, athermosetting resin, polyvinyl chloride, acrylic, polyimide, an epoxyresin, a silicone resin, polyvinyl butyral, or ethylene vinylene acetatecan be used, in addition to inert gas such as nitrogen or argon.

A structure of the element formation layer 300 is described below. Thepixel portion 302, the signal line driver circuit 303, and the scan linedriver circuit 304 each include a plurality of thin film transistors. InFIG. 31B, only a thin film transistor 308 included in the signal linedriver circuit 303 and a thin film transistor 310 included in the pixelportion 302 are shown. The pixel portion 302 includes a light-emittingelement 311, and the light-emitting element 311 is electricallyconnected to the thin film transistor 310.

A lead wiring 314 is a wiring for supplying a signal or power supply toa circuit in the element formation layer 300 from outside. The leadwiring 314 is connected to a connection terminal 316 of a two-layerstructure through a lead wiring 315 a and a lead wiring 315 b. Theconnection terminal 316 is electrically connected to a terminal includedin a flexible printed circuit (ITC) 318 through an anisotropicconductive film 319.

Example 7

A semiconductor device of the present invention includes electronicdevices provided with the liquid crystal module described in Example 5or the EL module described in Example 6 in a display portion.Hereinafter, a liquid crystal module and an EL module are collectivelyreferred to as a display module. As such an electronic device, there area monitor for a computer, a television set (also simply referred to as atelevision or a television receiver), a camera such as a digital cameraa digital video camera, a mobile phone set (also simply referred to as amobile phone or a cellular phone), a portable information terminal suchas a PDA (Personal Digital Assistant), a notebook computer, a car audiosystem, a navigation system, a digital music player, a portable DVDreproducing device, a portable game machine, an arcade game machine, andthe like. The specific examples will be described with reference toFIGS. 32A to 32C.

FIGS. 32A and 32B show television devices. As a structure of anincorporated display module, there are the following structures: astructure in which only a pixel portion is formed in an elementformation layer, and a scan line driver circuit and a signal line drivercircuit are mounted on a substrate; a structure in which a pixel portionand a scan line driver circuit are formed in an element formation layerand a signal line driver circuit as a driver IC is mounted on asubstrate; a structure in which a pixel portion, a signal line drivercircuit, and a scan line driver circuit are formed in an elementformation layer; and the like. The display module of the presentinvention can have any of the structures. Note that a scan line drivercircuit and a signal line driver circuit may be mounted on a substrateby a mounting method such as a TAB method or a COG method.

In the television device, as an external circuit other than a displaymodule, a video signal amplifier circuit which amplifies a video signalamong signals received by a tuner, a video signal processing circuitwhich converts the signals outputted from the video signal amplifiercircuit into chrominance signals corresponding to respective colors ofred, green, and blue, a control circuit which converts the video signalinto an input specification of the driver IC, and the like are providedon an input side of the video signal. The control circuit outputssignals to both a scan line side and a signal line side. In the case ofdigital drive, a signal dividing circuit can be provided on the signalline side and an input digital signal may be divided into a plurality ofnumbers and supplied.

An audio signal among signals received by the tuner is sent to an audiosignal amplifier circuit and an output of the audio signal amplifiercircuit is supplied to a speaker through an audio signal processingcircuit. A control circuit receives control information of a receivingstation (reception frequency) or sound volume from an input portion andtransmits signals to the tuner and the audio signal processing circuit.

As shown in FIGS. 32A and 32B, in the television device, a displaymodule is incorporated into a chassis. A main screen 403 is formed byusing the display module, and a speaker portion 409, an operationswitch, and the like are provided as its accessory equipment. Thus, atelevision device can be completed.

As shown in FIG. 32A, a liquid crystal module 402 is incorporated in achassis 401. General TV broadcast can be received by a receiver 405.When the display device is connected to a communication network by wiredor wireless connections via a modem 404, one-way (from a sender to areceiver) or two-way (between a sender and a receiver or betweenreceivers) information communication can be performed. The televisiondevice can be operated by using a switch built in the chassis 401 or aremote controller 406. A display portion 407 for displaying outputinformation can also be provided in the remote controller.

Further, the television device may include a sub screen 408 formed usinga second display panel so as to display channels, volume, or the like,in addition to the main screen 403. In this structure, the main screen403 may be formed using an EL module having a wide viewing angle, andthe sub screen 408 may be formed using a liquid crystal module capableof displaying images with less power consumption. In order to reduce thepower consumption preferentially, the main screen 403 may be formedusing a liquid crystal module, and the sub screen 408 may be formedusing an EL module, which can be switched on and off.

FIG. 32B shows a television device having a large-sized display portion,for example, a 20- to 80-inch display portion. The television deviceincludes a chassis 410, a keyboard portion 412 that is an operationportion, a display portion 411, a speaker portion 413, and the like. Adisplay module is used for the display portion 411. Since a bendabledisplay module is used for the display portion 411 in FIG. 32B, thetelevision device in which the display portion 411 is curved is formed.By using a flexible display module in this manner, a shape of thedisplay portion 411 is not limited to only a plane, and televisiondevices of various shapes can be manufactured.

Since a yield of the display module can be improved by the presentinvention, cost reduction can be achieved. Therefore, a televisiondevice using the present invention can be manufactured at low cost evenwhen a large screen display portion is included.

Naturally, the display module of the present invention is not limited tothe television device, and can be applied to various use applications asa large-sized display medium such as an information display board at atrain station, an airport, or the like, or an advertisement displayboard on the street, as well as a monitor of a personal computer.

A display module of the present invention can be applied to displayportions of various portable devices, such as a cellular phone or adigital camera. FIG. 32C shows a structural example of an e-book readeras an example of a portable device. The e-book reader includes a mainbody 421, display portions 422 and 423, a storage medium 424, anoperation switch 425, an antenna 426, and the like. When a flexibledisplay module is used for the display portion 422, a portable devicecan be reduced in weight.

Example 8

This example will explain that force to generate peeling can be weakenedand generation of damage such as breaking or a crack in the elementformation layer can be avoided by separating an element formation layerfrom a substrate while liquid is being supplied.

First, a method for manufacturing a sample with which a peel test wasperformed is described.

FIG. 33 is a diagram for illustrating a stacked structure of the samplewith which the peel test was performed. A glass substrate 500 wasprepared. As the glass substrate 500, non-alkaline glass (product name:AN100) made by Asahi Glass Co., Ltd. was used. The thickness is 0.7 mmand the size is 100 mm×120 mm.

Over the glass substrate 500, a silicon oxynitride (SiO_(x)N_(y), x>y)film 501 was formed having a thickness of 100 nm with a plasma CVDapparatus. As process gas for forming the silicon oxynitride film 501,SiH₄ and N₂O were used. Over the silicon oxynitride film 501, a tungstenfilm 502 having a thickness of 50 nm was formed with a sputteringapparatus. Tungsten was used as a target, and argon gas was used as gasfor discharge. The tungsten film 502 functions as a release layer.

Over the tungsten film 502, a stacked-layer film which is regarded as anelement formation layer and formed of an insulating film and asemiconductor film is formed. First, a silicon oxynitride (SiO_(x)N_(y),x>y) film 503 was formed having a thickness of 600 nm with a plasma CVDapparatus. As process gas to form the silicon oxynitride film 503, SiH₄and N₂O were used. In addition, before depositing the silicon oxynitridefilm 503 over the tungsten film 502, only N₂O gas was supplied to achamber in which the silicon oxynitride film 503 was formed, and N₂O gaswas excited to a plasma state; accordingly, the surface of the tungstenfilm 502 was oxidized, whereby a tungsten oxide was formed. This plasmatreatment is treatment for generating peeling at an interface betweenthe tungsten film 502 and the silicon oxynitride film 503, which ispreferential to the other interface.

By using SiH₄, H₂, NH₃ and N₂O for process gas, a silicon oxynitride(SiO_(x)N_(y), x<y) film 504 having a thickness of 100 nm was formedover the silicon oxynitride film 503 with a plasma CVD apparatus. Byusing SiH₄ and N₂O for process gas, a silicon oxynitride (SiO_(x)N_(y),x>y) film 505 having a thickness of 100 nm was formed over the siliconoxynitride film 504 with the plasma CVD apparatus. By using SiH₄ and H₂for process gas, an amorphous silicon film 506 having a thickness of 66nm was formed over the silicon oxynitride film 505 with the plasma CVDapparatus. The silicon oxynitride film 504, the silicon oxynitride film505, and the amorphous silicon film 506 were formed in the same chamberof the plasma CVD apparatus, and process gas to be supplied in thechamber was changed, whereby these films were formed in succession.

Next, by using SiH₄, H₂, N₂, NH₃ and N₂O for process gas, a siliconoxynitride (SiO_(x)N_(y), x<y) film 507 having a thickness of 100 nm wasformed over the amorphous silicon film 506 with the plasma CVDapparatus. By using SiH₄ and N₂O for process gas, a silicon oxynitride(SiO_(x)N_(y), x>y) film 508 having a thickness of 600 nm was formedover the silicon oxynitride film 507 with the plasma CVD apparatus.

Next, by irradiation of a UV laser beam from the glass substrate 500 andcutting the glass substrate 500 over which the films 501 to 508 wereformed, the size of a sample was set as a rectangle of 20 mm×100 mm.FIG. 34 is a plan view of the sample processed into a rectangular shape.Next, in order to form a trigger for peeling, a groove 510 which reachedthe tungsten film 502 was formed in the sample by UV laser beamirradiation, as shown in FIG. 34. By forming the groove 510, peeling isgenerated between the silicon oxynitride film 503 and the tungsten film502. The sample for a peel test was prepared by the above-describedmethod.

Next, a method of a peel test is described. Heat peeling tape having awidth of about 20 mm was prepared. As the heat peeling tape, elegriptape (item: FA1250) made by Denki Kagaku Kogyo Kabushiki Kaisha wasused. The total thickness of a base material of this heat peeling tapeand an adhesive layer is 150 μm, and a thickness of the adhesion layeris 50 μm. The base material of the heat peeling tape is formed of PET(polyethylene terephthalate).

The heat peeling tape was attached to the sample in which the groove hadbeen formed. The heat peeling tape is attached to a silicon oxynitridefilm 508 side. By peeling the heat peeling tape, the stacked-layer filmformed of the films 508 to 503 can be peeled from the substrate 500.

Tension which was required for peeling the stacked-layer film formed ofthe films 508 to 503 from the tungsten film 502 was measured by pullingthe heat peeling tape. For a peel test, a compact table-top universaltester (EZ-TEST EZ-S-50N) made by Shimadzu Corporation was used. As apeel test method, the adhesive tape/adhesive sheet test method based onstandard number of JIS Z0237 of Japanese Industrial Standards (JIS) wasused. Tension was measured in the case where peeling was performed whilepure water was being supplied to the sample and in the case wherepeeling was performed without supply of pure water. Note that supply ofpure water was performed by dropping pure water on a peeling portionwith a dropper after the sample was attached to the tester.

FIG. 35 is a graph showing a peel test result. A vertical axis of FIG.35 indicates tension applied to the heat peeling tape, and a horizontalaxis thereof indicates a stroke. The stroke shows displacement of thepoint of application of force, that is, displacement of the point wherepeeling is generated.

According to the graph of FIG. 35, it is found that tension in the casewhere pure water is supplied is ½ or less than that in the case wherepure water is not supplied. According to this peel test, it wasconfirmed that peeling was able to be performed with weaker force, bysupplying pure water.

In addition, when a peel test was performed without supply of purewater, the graph of FIG. 35 shows a sawtooth profile. The sawtoothprofile shows that peeling proceeds as follows. When peeling isperformed without supply of pure water, force which is stronger thanthat in the case where pure water is supplied so that peeling proceedsis applied at the point of application. However, when peeling proceeds,the force is suddenly reduced. Peeling proceeds while the increase offorce applied to such a point of application and sudden decrease arerepeated.

When the sample which was peeled without the supply of pure water wasobserved, it was confirmed that a crack was generated at a portion wheretension was suddenly reduced. On the other hand, a crack was notgenerated in the sample with which the peel test was performed whilepure water was being supplied. As described above, it was found thatgeneration of a crack can be prevented by performing peeling while purewater was being supplied.

Note that, although pure water is polar liquid, the peel test wasperformed while nonpolar liquid having a nonpolar medium was beingsupplied for comparison. For example, as liquid, hydrofluoroether (HFE)was used. In the case where the peel test was performed while HFE wasbeing supplied, tension which was larger than that in the case whereliquid was not supplied was required in order to perform peeling. In thecase of using benzene, a similar result to that of the case of usingFIFE was obtained.

The following was found from the above peel test. When peeling isperformed by supplying polar liquid such as pure water, an aqueoussolution, ethanol, or acetone, discharge by peeling electrification canbe eliminated; in addition, force required for peeling can be reducedand generation of damage such as a crack in an object to be peeled canbe prevented.

This application is based on Japanese Patent Application serial No.2006-266543 filed in Japan Patent Office on Sep. 29, 2006, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, comprising: forming a metal layer over a substrate; oxidizing asurface of the metal layer; forming an element formation layer includinga semiconductor element over the metal layer; forming a groove in theelement formation layer; supplying liquid to at least a portion wherethe groove is formed; separating the element formation layer from thesubstrate, while a surface which is exposed by the separating is wettedwith the liquid as the separation advances after stopping supply of theliquid; and fixing a flexible substrate to the element formation layer,after the separating step.
 2. The method for manufacturing asemiconductor device according to claim 1, wherein the liquid is purewater.
 3. The method for manufacturing a semiconductor device accordingto claim 1, wherein the element formation layer comprises an integratedcircuit.
 4. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the liquid spreads due to a capillaryphenomenon.
 5. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the element formation layer is separatedfrom the substrate at an interface between the metal layer and theelement formation layer.
 6. The method for manufacturing a semiconductordevice according to claim 1, wherein the element formation layer isseparated from the substrate at an interface between the metal layer andthe substrate.
 7. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the step of supplying the liquid and thestep of separating the element formation layer are performedsimultaneously.
 8. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the semiconductor device is a displaydevice.
 9. The method for manufacturing a semiconductor device accordingto claim 1, wherein the metal layer comprises a metal selected from thegroup consisting of tungsten, molybdenum, titanium, tantalum, niobium,nickel, cobalt, zirconium, zinc, ruthenium, rhodium, palladium, osmium,iridium, or an alloy thereof.
 10. The method for manufacturing asemiconductor device according to claim 1, wherein oxidation of thesurface of the metal layer is performed by treating the surface with anoxygen containing plasma.
 11. The method for manufacturing asemiconductor device according to claim 1, wherein the liquid issupplied by spraying in an atomized form.
 12. The method formanufacturing a semiconductor device according to claim 1, wherein theliquid is supplied by spraying in a vaporized form.
 13. A method formanufacturing a semiconductor device, comprising: forming a metal layerover a substrate; oxidizing a surface of the metal layer; forming anelement formation layer including a semiconductor element over the metallayer; generating peeling so that the element formation layer isseparated from the substrate; supplying liquid to a portion where thepeeling is generated; separating the element formation layer from thesubstrate, while a surface which is exposed by the separating is wettedwith the liquid as the separation advances after stopping supply of theliquid; and fixing a flexible substrate to the element formation layer,after the separating step.
 14. The method for manufacturing asemiconductor device according to claim 13, wherein the liquid is purewater.
 15. The method for manufacturing a semiconductor device accordingto claim 13, wherein the element formation layer comprises an integratedcircuit.
 16. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein the liquid is supplied by spraying in avaporized form.
 17. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein the liquid spreads due to a capillaryphenomenon.
 18. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein the element formation layer is separatedfrom the substrate at an interface between the metal layer and theelement formation layer.
 19. The method for manufacturing asemiconductor device according to claim 13, wherein the elementformation layer is separated from the substrate at an interface betweenthe metal layer and the substrate.
 20. The method for manufacturing asemiconductor device according to claim 13, wherein the step ofsupplying the liquid and the step of separating the element formationlayer are performed simultaneously.
 21. The method for manufacturing asemiconductor device according to claim 13, wherein the semiconductordevice is a display device.
 22. The method for manufacturing asemiconductor device according to claim 13, wherein the metal layercomprises a metal selected from the group consisting of tungsten,molybdenum, titanium, tantalum, niobium, nickel, cobalt, zirconium,zinc, ruthenium, rhodium, palladium, osmium, iridium, or an alloythereof.
 23. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein oxidation of the surface of the metallayer is performed by treating the surface with an oxygen containingplasma.
 24. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein the liquid is supplied by spraying in anatomized form.